Dietary Nut and Legume Intake and Risk of Inflammatory Bowel Disease in US Adults

Year Published: 2023

Journal

Gastroenterology

Authors

Lopes, Emily MD, MPH*; Yu, Zeling BS; Burke, Kristin MD, MPH; Richter, James MD; Ananthakrishnan, Ashwin MD, MPH; Chan, Andrew MD, MPH; Khalili, Hamed MD, MPH

Methods

Introduction: Several dietary risk factors have been identified for Crohn’s disease (CD) and ulcerative colitis (UC). Nuts and legumes may possess anti-inflammatory effects either directly or by impacting the intestinal microbiota. To date, no prospective studies have investigated the relationship between nut and legume intake and risk of CD or UC. Methods: We conducted a prospective cohort study of 129,784 US adults from the Nurses’ Health Study and Health Professionals Follow-Up Study between 1986-2016. We excluded those with CD or UC at baseline. Semiquantitative food frequency questionnaires completed every 4 years were used to calculate cumulative average of daily servings of dietary nut and legume intake. CD and UC were self-reported on follow-up questionnaires and confirmed via blinded record review by 2 gastroenterologists. Cox proportional hazards models were used to calculate multivariable-adjusted hazard ratios (aHR) and 95% confidence intervals (CI) for CD and UC according to quintiles of nut or legume intake.

Key Findings

Key Findings: Results: We ascertained 211 CD cases and 240 UC cases over 3,213,883 person-years. Nut intake was associated with decreased risk of CD, though this did not reach statistical significance (Ptrend=0.06; Table 1). Compared to those in the lowest quintile of nut intake (mean=0 servings/day), those in the highest quintile (mean=0.60 servings/day) had an aHR of 0.71 (95% CI 0.43-1.15) for CD. No association was seen between nut intake and risk of UC (aHR for highest compared with lowest quintile=1.29 (95% CI 0.81-2.04), Ptrend=0.28). Legume intake was associated with a decreased risk of UC, though this did not reach statistical significance (Ptrend=0.09). Compared to those in the lowest quintile of legume intake (mean=0.04 servings/day), those in the highest quintile (mean=0.57 servings/day) had an aHR of 0.72 (95% CI 0.45-1.15) for UC. No association was seen between legume intake and risk of CD (aHR for highest compared with lowest quintile=0.98 (95% CI 0.60-1.58), Ptrend=0.72). In stratified analysis, baseline age, smoking status, and body mass index did not modify the relationship between nut or legume intake and risk of CD or UC (all Pinteraction≥0.16). Conclusion: In 2 large, prospective cohorts in the US, dietary nut intake was associated with a trend toward decreased risk of CD and dietary legume intake was associated with a trend toward decreased risk of UC. Additional prospective or interventional studies are needed to expand upon these findings.